WASHINGTON (AP) -- Interracial marriages in the U.S. have climbed to 4.8 million - a record 1 in 12 - as a steady flow of new Asian and Hispanic immigrants expands the pool of prospective spouses. Blacks are now substantially more likely than before to marry whites.

A Pew Research Center study, released Thursday, details a diversifying America where interracial unions and the mixed-race children they produce are challenging typical notions of race.

"The rise in interracial marriage indicates that race relations have improved over the past quarter century," said Daniel Lichter, a sociology professor at Cornell University. "Mixed-race children have blurred America's color line. They often interact with others on either side of the racial divide and frequently serve as brokers between friends and family members of different racial backgrounds," he said. "But America still has a long way to go."

The figures come from previous censuses as well as the 2008-2010 American Community Survey, which surveys 3 million households annually. The figures for "white" refer to those whites who are not of Hispanic ethnicity. For purposes of defining interracial marriages, Hispanic is counted as a race by many in the demographic field.

The study finds that 8.4 percent of all current U.S. marriages are interracial, up from 3.2 percent in 1980. While Hispanics and Asians remained the most likely, as in previous decades, to marry someone of a different race, the biggest jump in share since 2008 occurred among blacks, who historically have been the most segregated.

States in the West where Asian and Hispanic immigrants are more numerous, including Hawaii, Nevada, New Mexico and California, were among the most likely to have couples who "marry out" - more than 1 in 5. The West was followed by the South, Northeast and Midwest. By state, mostly white Vermont had the lowest rate of intermarriage, at 4 percent.

In all, more than 15 percent of new marriages in 2010 were interracial.

The numbers also coincide with Pew survey data showing greater public acceptance of mixed marriage, coming nearly half a century after the Supreme Court in 1967 barred race-based restrictions on marriage. (In 2000, Alabama became the last state to lift its unenforceable ban on interracial marriages.) About 83 percent of Americans say it is "all right for blacks and whites to date each other," up from 48 percent in 1987. As a whole, about 63 percent of those surveyed say it "would be fine" if a family member were to marry outside their own race.

Minorities, young adults, the higher educated and those living in Western or Northeast states were more likely to say mixed marriages are a change for the better for society. The figure was 61 percent for 18- to 29-year-olds, for instance, compared to 28 percent for those 65 and older.

Due to increasing interracial marriages, multiracial Americans are a small but fast-growing demographic group, making up about 9 million, or 8 percent of the minority population. Together with blacks, Hispanics and Asians, the Census Bureau estimates they collectively will represent a majority of the U.S. population by mid-century.

"Race is a social construct; race isn't real," said Jonathan Brent, 28. The son of a white father and Japanese-American mother, Brent helped organize multiracial groups in southern California and believes his background helps him understand situations from different perspectives.

Brent, now a lawyer in Charlottesville, Va., says at varying points in his life he has identified with being white, Japanese and more recently as someone of mixed ethnic background. He doesn't feel constrained with whom he socially interacts or dates.

"Race is becoming a personal thing. It is what I feel like I am," he said.

According to the Pew report, more than 25 percent of Hispanics and Asians who married in 2010 had a spouse of a different race. That's compared to 17.1 percent of blacks and 9.4 percent of whites. Of the 275,500 new interracial marriages in 2010, 43 percent were white-Hispanic couples, 14.4 percent were white-Asian, 11.9 percent were white-black, and the remainder were other combinations.

Still, the share of Asians who intermarried has actually declined recently - from 30.5 percent in 2008 to 27.7 percent in 2010. In contrast, blacks who married outside their race increased in share from 15.5 percent to 17.1 percent, due in part to a rising black middle class that has more interaction with other races.

Intermarriage among whites rose in share slightly, while among Hispanics the rate was flat, at roughly 25.7 percent.

"In the past century, intermarriage has evolved from being illegal, to be a taboo and then to be merely unusual. And with each passing year, it becomes less unusual," said Paul Taylor, director of Pew's Social & Demographic Trends project. "That says a lot about the state of race relations. Behaviors have changed and attitudes have changed."

He noted that interracial marriages among Hispanics and Asians may be slowing somewhat as recent immigration and their rapid population growth provide minorities more ethnically similar partners to choose from. But Taylor believes the longer-term trend of intermarriage is likely to continue.

"For younger Americans, racial and ethnic diversity are a part of their lives," he said.

The Pew study also tracks some divorce trends, citing studies using government data that found overall divorce rates higher for interracial couples. One study conducted a decade ago determined that mixed-race couples had a 41 percent chance of separation or divorce, compared to a 31 percent chance for those who married within their race.

Another analysis found divorce rates among mixed-race couples to be more dependent on the specific race combination, with white women who married outside their race more likely to divorce. Mixed marriages involving blacks and whites also were considered least stable, followed by Hispanic-white couples.

Other findings:

-Broken down by gender, black men were more than twice as likely as black women to marry someone outside their race - 24 percent to 9 percent. The reverse held true for Asian men - 17 percent intermarried, compared to 36 percent among Asian women.